1. Field of the Invention
The present invention relates to paper machine clothing, and more particularly, to a process for preparing a seam area for the clothing in an endless manner.
2. Description of the Related Art
A paper machine clothing (PMC) base fabric is typically manufactured with a specific set of design and quality specifications for a particular paper machine's performance requirements. These specifications include surface characteristics, open area, void volume, permeability and smoothness, among others.
It is known to manufacture a woven press fabric having a flat woven base fabric with a plurality of warp yarns forming seam loops along the ends of the fabric extending in a cross machine direction, transverse to the machine direction. The ends are then placed in end-to-end disposition in order to interdigitate the loops and a pintle wire is then inserted in the interdigitated loops to lock the ends together to bring the fabric into an endless form. For installation in a paper machine of the like, the two ends are separated such that the fabric can be pulled in its direction of movement into the machine, after which the two belt longitudinal ends can then be joined together again. The region of the seam in this case has a larger void area than the rest of the fabric, resulting in a differential dewatering in this area which may lead to marking of the fibrous web. In addition, the formation of seam loops on the base fabric results in increased production time and expense.
PCT Intl. App. No. PCT/GB89/00681, which is assigned to the assignee of the present invention, discloses a seam for a PMC base fabric in which a number of weft yarns are removed from the fabric at a fold location. The fabric is folded over at the fold location, sewed adjacent the fold location, interdigitated with loops from an adjacent fabric end, and a pintle wire is inserted through the interdigitated loops. There is no attempt to align the weft or warp yarns of the folded fabric adjacent the fold location. This configuration provides an effective seam, but the randomly aligned yarns on either side of the window can provide some variability of the seam properties.
What is needed in the art is an improved process for preparing a seam area for a PMC base fabric.